Ceramics are important candidates for applications where high temperatures and high stresses are present, because of their good resistance to oxidation and their desirable elastic properties. However, they are also brittle and, therefore, can be used in high stress and high temperature applications only as part of a multi-phase microstructure, frequently in the form of a metal-matrix ceramic composite. While such microstructures can, in principle, be produced with current technology by combining previously prepared fibers and metal powders, the cost per pound is high and, if they are to be used broadly, there is a pressing need for new processes to fabricate such materials economically.
Processes are known where metal-ceramic oxide structures are formed in situ. Funkhauser et al. U.S. Pat. No. 3,024,110 and Edstrom U.S. Pat. No. 3,044,867 disclose processes where a solid solution of oxide compounds or an oxide compound, containing a more noble metallic component in substantial amount more than a less noble metallic component, is subjected to reducing conditions to convert the more noble metallic component entirely to elemental metal to form a mass of metal containing therein particles of ceramic oxide. Humenik, Jr., et al. U.S. Pat. No. 3,369,877 discloses a process where an aluminum component is present in substantial amount more than a molybdenum or a tungsten component and the molybdenum or tungsten component is entirely converted to elemental metal and the product is a mass of aluminum oxide ceramic containing fine elemental metal molybdenum or tungsten particles therein. These processes lack flexibility because the resulting microstructure depends entirely on the ratio of metallic elements in the starting material.